Military vehicles are sometimes equipped with heavy main guns designed to fire high explosive shells over relatively long distances (one or more miles). Such vehicles sometimes are capable of fairly high road speeds, e.g., thirty-five miles per hour.
The heavy main gun on a given vehicle can project (extend) a considerable distance from the associated gun turret, e.g., twenty or more feet. During vehicle travel over rough terrain the muzzle end of the heavy gun functions somewhat like a heavy pendulum. The gun tends to swing up and down so as to induce a rocking or pitching motion in the moving vehicle. Considerable strain is placed on the turret structure, the gun elevating mechanism, and possibly the vehicle suspension. Additionally, the vehicle occupants are jolted back and forth, with some physical discomfort. In some cases it may be necessary to run the vehicle at an undesirably low road speed in order to minimize some or all of the undesired effects.
To minimize the undesired pendulum motion of the gun barrel some vehicles have been equipped with travel locks. A travel lock comprises an elongated arm structure mounted at or near the front end (nose) of the vehicle hull on the longitudinal axis of the vehicle, i.e., directly under the main gun when the gun is in its straight-ahead position. The travel lock arm structure can be swung in a vertical plane between an inactive prone position lying against the upper external surface of the hull and an upright active position extending upwardly toward the barrel of the main gun.
The free end of the travel lock arm structure has a concave seat conforming to the contour of the gun barrel, whereby when the arm structure is in its upright position the heavy gun can be lowered so that the gun barrel undersurface rests against the concave seat. A semi-circular clamp arm is pivotally attached to the upper end of the arm structure at a point near the concave seat, such that the clamp arm can be manually swung up and over the gun barrel; the concave surface of the clamp arm engages the upper surface of the gun barrel to prevent upward dislocation of the barrel from the aforementioned concave seat. A toggle bolt releasably secures the free end of the clamp arm to the travel lock proper.
When the vehicle is operating under battlefield conditions (firing mode) the travel lock is manually disengaged from the gun barrel and swung down to a prone (inactive) position lying against the hull upper face.
In its operating position the travel lock acts as a rigid link between the nose end of the hull and a mid point on the barrel (forward from the turret). The travel lock thus provides a second support point for the gun, forwardly from the gun trunnions. The effective length of the aforementioned pendulum is considerably reduced so that disturbing forces on the vehicle-gun components are greatly reduced. Performance of the vehicle suspension is improved, with less rocking (pitching) motion of the vehicle, and less physical discomfort to the passengers.
A principal disadvantage of existing external travel locks is the fact that in order to switch the lock between the active (upright) position and the inactive (prone) position it is necessary for one or more soldiers to disembark from the vehicle to lock/unlock the clamp arm and swing the arm structure up or down onto the hull. The operation is somewhat time-consuming. More importantly, if the operation is carried out in/near a battle zone the disembarked soldiers are exposed to enemy fire; additionally the vehicle is required to be in a stand-still attitude vulnerable to enemy attack.
The present invention is directed to an external travel lock that is remotely operable from within the vehicle. Such remote operation is advantageous in that no soldiers are exposed to enemy fire while the travel lock is being adjusted between its active (barrel-lock) mode and inactive mode. It is possible to carry out the operation while the vehicle is moving, whereby the vehicle has lessened exposure to enemy fire.
The invention was conceived especially for use with U.S. military vehicles designated as the M109A2 and M109A3. Each of these vehicles is a tracked vehicle having a 155 mm howitzer main gun mounted on an armored turret. It is believed that the invention could be used on other military vehicles.